Table 4.
Actinic keratosis (AK)‐related healthcare visits and subsequent (pre)malignancies among patients with AK
| Database | GP records | Dermatologist records | |
|---|---|---|---|
| Routine GP records (IPCI) | Rotterdam Study | Claims data (DIS) | |
| Patients, n | 486d | 266 | 200 056 |
| Follow‐up time (years) | Median 5·6, IQR 5·1–6·2 | Median 2·8, IQR 1·3–4·4 | Up to 5 yearse |
| Follow‐up | |||
| Number of AK‐related follow‐up visits | |||
| 0 | 149 (31) | 166 (62) | 87 302 (44) |
| ≥ 1 | 337 (69)a | 100 (38) | 112 754 (56) |
| Visits per period, n (%) | N/A | 189 visits in 100 patients | 317 642 visits in 112 754 patients |
| <3 months | – | 46 (24) | 101 382 (32) |
| 3–12 months | – | 42 (22) | 86 766 (27) |
| > 12 months | – | 94 (50) | 129 494 (41) |
| Unknown | – | 7 (4) | 0 (0) |
| Cutaneous lesions | |||
| Subsequent cutaneous malignancy, n (%) | 138 (10) of 1322b | 19 178 (11)c | |
| Basal cell carcinoma | 72 (15) | 88 (7) | N/A |
| Squamous cell carcinoma | 36 (7) | 50 (4) | N/A |
DIS, DRG Information System; GP, general practitioner; IPCI, Integrated Primary Care Information; IQR, interquartile range; N/A, not applicable. a486 patients with confirmed AK in the cohort 2009/2010. bAll patients were followed up to mid‐2016, independent of the year of initial treatment. cTotal of patients with one or more skin cancer related GP visits (not AK specific). dCases were identified using linkage with the Dutch Pathology Registry (PALGA) in the period from the date of skin screening based AK diagnosis until the end of 2015. Median follow‐up period for this group is 3·7 (IQR 1·3–4·6). eIncludes patients with a subsequent claim for diagnostic code 0017 for cutaneous malignancy, including basal cell carcinoma, squamous cell carcinoma, (lentigo maligna) melanoma, lymphoma, cutaneous metastatic disease and other cutaneous malignancies; no further differentiation available. Only the first claim for cutaneous malignancy could be extracted.